With the continuous development of the oil well completion technique, the number of some complex wells, such as ultra-deep wells, horizontal wells, extended reach wells, high-pressure wells, is increasing, and the hanging screen well completion technique plays a big role in solving complex problems of the well-completion practice. The liner hanger packer is a key to hanging screen well completion.
According to a product sample introduction published by TIW Corporation (US) in 1997, the product from that company is such a product that a packing segment is arranged at an upper end of a hanging apparatus, the packing segment is sleeved with several plastic cylinders with their lower ends abutting against a shoulder and upper ends pressed by a locking sleeve. The hanging apparatus is in a cylindrical shape with its upper end connecting with a sealing apparatus, and an upper end of the locking sleeve is connected with a tie-back receptacle. During assembly, the locking sleeve and the hanging apparatus is fixed and thus prevented from relative sliding by a pin arranged therebetween, allowing the plastic cylinder to be in an unstressed condition. When descending the well for packing, the tie-back receptacle pushes the locking sleeve downward to shear the pin, and the locking sleeve moves downward to press the plastic cylinder so as to cause radial expansion of the latter, thereby packing an annular space between the liner and an outside casing. A retaining apparatus is arranged below an inner circle of the locking sleeve to allow for a downward movement of the locking sleeve but not a reverse movement, so that the plastic cylinder cannot rebound, and the annular space is effectively packed.
However, such a product has a disadvantage that as the diameter of an outer rim of the plastic cylinder is the same as that of the liner and the locking sleeve, damage occurs when this apparatus descends the well, thereby affecting the packing effect. During a descent process, a premature activation is caused easily, thus leading to accidents.
How to improve the reliability and security of base sealing and base hanging has always been a big problem that manufacturers of liner hanger packers are facing. For many years, many domestic and foreign manufacturers have offered one after another new-type liner hanger packers with unique structures, but due to the influence of the severe downhole environment, premature base-hanging and base-sealing during a descent process of the liner hanger packer has always been a big technical disadvantage in the application of the liner hanger packer.